ANALYSYS & OPTIMIZATION OF HYDRAULIC EXCAVATOR BUCKET TEETH USING FEM

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1 ANALYSYS & OPTIMIZATION OF HYDRAULIC EXCAVATOR BUCKET TEETH USING FEM Shailesh sharma 1, Alok Sharma 2 1,2 Mechanical Engineering Department, SSTC Bhilai Abstract In this paper various configurations of the bucket teeth have been designed in order to perform static analysis. The analysis has been carried out by using ANSYS14.5 where various configurations of teeth are designed as per SAE J1179 standard and using boundary condition for the maximum digging force condition all the design teeth are subject to maximum force. The effect of maximum digging force has been observed on maximum tooth deformation and Maximum Equivalent Von-Mises stress. In order to validate the obtained results are compared with the available literature and the results are within acceptable limit. Moreover, the effect of fillet on the teeth tip has been observed in terms of maximum total deformation and Von mises stresses. And the optimum condition of the fillet has been proposed for the all the configuration of the bucket teeth. Keywords Bucket excavator, Bucket Teeth, Deformation, Failure teeth I. INTRODUCTION A hydraulic excavator (digger) is an outsized vehicle that is build up for demolition and excavation purposes. A conventional hydraulic excavator consists of various parts but the basic prime parts are boom, chassis, and bucket, and move using wheels or tracks. They are available in a wide range in size and function, an instance of which is the comparable but smaller mini excavator. All versions are usually designed for the same intentions. Hydraulic excavators weigh lying 3,000 and 2 million pounds and their speed varies between 19 HP and 5,000 HP. Conventionally, Hydraulic excavator bucket is made up of selling steel and normally tooth present, which is protruding from the cutting edge, is to disrupt hard material and prevents from wearing-and-tearing of the bucket. The excavator bucket tooth has to stand heavy loads of materials, for example, wet soil and rock furthermore, it also subjected to abrasion wear because of the abrasive nature of soil particles when tooth acting to disintegrate material. Generally, for making tooth of excavator bucket alloy steel is used along with the addition of some other wear resistant materials so that its life will improve against abrasive wear. Using alloy along with solid steel is basically due to having both good toughness and abrasive resistance as of having direct contact of metallic components with the soil constituents. Therefore, better selection of tooth material and tooth design should be undertaken in order to prevent from bucket tooth failure. II. LITERATURE REVIEW Maciejewski et al conduct an experiment to investigate soil cutting problem. And concluded that the tool width equalled the width of the soil bin, the soil cutting problems might be treated as plane strain processes. Moreover in their next paper they conduct a new experiment to analyze the bucket equipped with teeth. And the effect of no. of teeth and teeth spacing has been examined in order to enhance the digging cycle efficiency. Coetzee et al.2007 presents an 2Dimensional discrete and continuum modelling of excavator bucket filling. Discrete element method and material-point method are used and compared with experimental results and conclude that The DEM model does not accurately predict the material flow during filling, while the polar and non-polar techniques are more accurate. DOI : /IJRTER XNO0N 267

2 Knight 2009 analyzed the shovel dipper teeth and evaluate the Optimal replacement intervals. a novel technique called grouped failure data with multiple suspensions has been used and conclude that using this replacement interval a saving of US$ 300,000 per shovel per year can be achieved. Eugeniusz et al 2010 examined the failure caused by fractured shaft of the bucket wheel. To analyze the failure discrete model has been developed and using FEM technique analysis has been carried out. At the fractured region Macroscopic and microscopic image has been taken o analyze the microscopic characteristics so that such failure of shaft can be be prevented in future. Jovancic et al diagnose Load-Bearing capacity of bucket wheel excavator and found that the force exerted during excavation operation are required to find these forces for better design of tool, backhoe parts and for trajectory planning. Miodrag et al examined the failure of bucket wheel caused by residual stresses in welded joints using FEM approach. The results are compared with the numerical experimental result and revealed that the combination of working (dynamic) and residual (static) stress can be over the limit lines of modified Goodman s. Babu and Venu et al.2014 optimized the excavator bucket using finite element method. They develop and bucket for PC-09 and Zaxis-8-1 using solid works and imported in ANSYS for transient analysis. They modified some parameters and proposed a optimum design. Kalpak et al 2015 The Excavator bucket tooth have to bear heavy loads of materials like soil, rock and subjected to abrasion wear due to the abrasive nature of soil particles. Its tooth got damaged due to abrasive wear and impact load. This paper deals with review of Excavators bucket tooth analysis to find out its actual failure. III. METHODOLOGY The Bucket teeth has been modeled by using ANSYS 14.5 and it is was discretized into 7208 elements with nodes For bending and contact stress analysis of the bucket tooth the material properties has been tabulated in table 5.1 and the dimensions of the teeth are detailed in figure 1 the develop teeth are as per SAE standards. The meshed teeth in ANSYS 14.5 is shown in figure 2. The boundary condition applied to the teeth is detailed in Figure 3 Table 5.1 Tooth Material properties [10, 11, 12] Properties Alloy steel Hardox 500 Density (kg/ m3) 7850 Modulus of elasticity (MPa) 2.1*105 Poisson's ratio 0.29 Yield strength (MPa) 1000 Ultimate tensile strength(mpa) 1250 Impact toughness (J) 30 Brinell hardness All Rights Reserved 268

3 Figure 1 Tooth Dimension [10, 12] Standard All Rights Reserved 269

4 Fanggs Digg Teeth Long Teeth Twin Tiger All Rights Reserved 270

5 Tiger Teeth Figure 2 Meshed Teeth Figure 3 Boundary condition for tooth IV. Result and Discussion Figure 4 Validation of Maximum total deformation with respect to different tooth All Rights Reserved 271

6 Figure 5 Validation of Maximum Equivalent Von-mises stress with respect to different tooth configuration Figure 4-5 shows the validation of Maximum total deformation and Maximum Equivalent Von- Mises stress with respect to different tooth configuration. It has been observed that the obtained results from Present finite analysis (ANSYS) of various tooth has been compared with the work of Bilal and Abid [10] and observed that the result shows good agreement and are in the acceptable range. Percentage variation has also been tabulated and it has been observed that the maximum deviation in maximum total deformation has been seen for Long Teeth i.e. ±14%.While minimum for Tiger teeth i.e. ±0.41%. Similarly for Maximum Equivalent Von-Mises stress maximum total deformation has been seen for Fanggs Digg Teeth i.e. ±9.68%.While minimum for Abbrasion teeth i.e. ±0.42%. The variations in results are mainly due to different mesh sizing and taken assumptions during analysis. Figure 6.and 7 illustrates the effect of Fillet radius on the Maximum total deformation and Maximum Equivalent Von-Mises stress of the Tiger Teeth. It has been observed that the the Maximum total deformation and Maximum Equivalent Von-Mises stress drastically decreases as the fillet radius increases. This means that introducing fillet reduce the stress level at the tip of the tooth. It has been analyzed that fillet radius above 1mm to 4mm the teeth are under safe zone and can withstand wide range of force. From the above, it can also be concluded that increasing fillet radius from 2mm to 4mm i.e. (100%), the stress level can be decreased by % respectively. Similarly, the rate of deformation can also be reduced by All Rights Reserved 272

7 Figure 6 Effect of Fillet radius on the Maximum total deformation and Maximum Equivalent Von-mises stress of the Tiger Teeth Figure 6.18 Effect of different fillet radius on the Maximum Equivalent Von-Mises stress of the Tiger All Rights Reserved 273

8 Figure 7 Effect of different fillet radius on the Maximum Equivalent Von-Mises stress of the Tiger Teeth V. CONCLUSIONS On the basis of finite element analysis of exactor bucket teeth following conclusions has been drawn which are as follows: The obtained result has been compared with the Bilal and Abid [18] and shows good agreement and varies in the range of ±0.2-±14. The effect of introducing fillet at the tip of the teeth has been observed for all configurations of the teeth and it has observed that majorly in most of the cases increasing fillet radius the Maximum total deformation and Maximum Equivalent Von-mises stress decreases significantly. It can be concluded that the fillet radius 0 to 1mm the teeth s are un-safe and has maximum possibility of failure. While, for fillet radius 2 to 4mm the teeth s are under safe limit. This is due to their Von-mises stress lying below their maximum yield strength. i.e. 1000/2 =500MPa, where 2 is factor of safety. It has been observed that the twin tiger tooth is not suitable for excavation of rigid surface. As it can be used for excavation of densely compacted soil/material normally in such cases, teeth are not subjected to such high force. It has been found that the optimum fillet radius should be taken between 2-3mm REFERENCES [1] J. Maciejewski, A. Jarzebowski, W. Tra mpczynski, Study on the efficiency of the digging process using the model of excavator bucket, Journal of Terramechanics 40 (2004) [2] C.J. Coetzee, A.H. Basson, P.A. Vermeer, Discrete and continuum modelling of excavator bucket filling, Journal of Terramechanics 44 (2007) [3] C.J. Coetzee *, D.N.J. Els, The numerical modelling of excavator bucket filling using DEM, Journal of Terramechanics 46 (2009) [4] P.F. Knights, Optimal replacement intervals for shovel dipper teeth, International Journal of Mining, Reclamation and Environment, Vol. 23, No. 3, September 2009, [5] Eugeniusz Rusin ski, Piotr Harnatkiewicz, Marcin Kowalczyk, Przemysław Moczko, Examination of the causes of a bucket wheel fracture in a bucket wheel excavator, Engineering Failure Analysis 17 (2010) 1300 All Rights Reserved 274

9 [6] Jovancic, P.D., Ignjatovic, D., Tanasijevic, M., and Maneski, T., Load-Bearing Steel Structure Diagnosticson Bucket Wheel Excavator, for the Purpose of Failure Prevention, Engineering Failure Analysis, 2011, vol. 18, pp [7] Miodrag Arsic, Srd-an Bošnjak, Nenad Zrnic, Aleksandar Sedmak, Nebojša Gnjatovi, Bucket wheel failure caused by residual stresses in welded joints, Engineering Failure Analysis 18 (2011) [8] S.Sekhar Babu, Y.Venu, Design optimization of excavator bucket using Finite Element Method, International Journal of Research and Innovation (IJRI),Volume: I, Issue : IV, December 22, 2014 [9] Kalpak. S. Dagwar, R.G. Telrandhe, Excavator Bucket Tooth Failure Analysis, International Journal of Research in Mechanical Engineering & Technology, IJRMET Vol. 5, Issue 2, May - Oct 2015 ISSN : (Online) ISSN : (Print) [10] Bilal Pirmahamad Shaikh and Abid M. Mulla, Analysis of Bucket Teeth of Backhoe Excavator Loader and its Weight Optimization, International Journal of Engineering Research & Technology (IJERT), Vol. 4 Issue 05, May-2015 [11] Hydraulic Excavator and Backhoe Digging Forces (Cancelled Mar 2008, Superseded by ISO 6015) [12] All Rights Reserved 275